Support base-url & context-path configurations

[a459259]

Feature Request

What challenge are you facing?

Centrally owning several Concourse clusters for various teams usually means owning a lot of infrastructure. A single cluster would usually have a global traffic manager and a certificate, as you start to have multiple clusters it becomes less desirable to have a GTM and certificate per cluster. It would be more desirable to have a single base url and allow forwarding on the context path.

A Modest Proposal

It would be great if base-url and context-path are supported/configurable variables in a Concourse deployment. Accessible urls could look something like this:

concourse.com/westworld/teams/abernathy
concourse.com/shogunworld/teams/samurai

[topherbullock]

Spoke about this with @cirocosta yesterday, and did a little bit of POC on a "Concourse Portal".

Creating a "Concourse Portal" to many the web UIs under sub-paths should be fairly simple as it's all Layer 7 proxying. The web instances would need to know somehow that they were being proxied to by this portal

The biggest design challenge to overcome is how to organize the TSA(s) for each child Concourse and how external workers register. As they're talking TCP, there's no clean way to proxy at the transport layer to ensure that our portal Concourse can route connections to the proper TSA without doing some dance down to the application layer and back.

One option we floated the idea that the portal to manage a pool of TCP proxies for each child. This would mean additional effort on the operator to expose this list of ports which are then mapped to the TSA(s) of the individual Concourses

Another option is to leave managing TCP load balancers for each child's TSA(s) to something external from the portal itself, and give external workers the load balancer address for their registration.

Did I miss anything @cirocosta ?